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Lawncheck Weather Setup and Discussion

LawnCheck can retrieve local, recently updated weather forecasts and apply the forecast information to your irrigation programs to reduce your water usage and reduce your water bill.

LawnCheck lets you use weather parameters like temperature, PoP (probability of precipitation), and conditions/outlook so you can minimize your water use. Using the forecast can also drastically reduce the frustration caused by events like having your irrigation run right before or right after a rain storm. No one wants that!.

Review this page to find out how LawnCheck retrieves local forecasts using the most accurate services available in the world today and lets you easily apply these forecasts to your irrigation programs.

How LawnCheck Applies the Weather Forecast

Here's a summary of how LawnCheck applies weather information to your irrigation system:

You can easily customize how these dependencies are applied by setting thresholds. For example, you could set a Hot Weather Activation temperature to 90 F, apply to one of your programs and the program will run only if the forecast high is 90 or more. LawnCheck makes it easy to apply weather to your irrigation.

How Does LawnCheck Get Local Weather Information?

LawnCheck has access to weather feeds from providers like Yahoo! Weather, DarkSky, and Weather Underground. These services offer local weather forecasts based on national public and private weather data. To get a local forecast you just need to provide a code that identifies your location. For Yahoo, this is the WOEID (Where On Earth ID). Its very easy to get a WOEID for your location.

The DarkSky weather service offers local weather based on a latitude and longitude point. You can easily get this location point from Google Maps.

WeatherUnderground offers a free weather feed for personal weatherstation owners who upload data to their network. You must obtain a free PWS key from them. Then you can select a station from their WunderMap to receive local weather and forecasts.

See below for more specific information about how to get a location code for your LawnCheck installation.

When is the Weather Retrieved?

The weather forecast is checked prior to a program start time. In addition, the weather forecast is retrieved a minimum of once a day, at approximately 10 o'clock PM local time. NOTE: typically an irrigation cycle command is sent to the controller about 50 minutes prior to the programmed start time, so the pre-cycle weather check is made about 50 minutes prior to the start time.

The remainder of this page provides more specific information about selecting a weather feed, getting a location ID, and specifics about how LawnCheck makes decisions about when to run or block a program that has weather dependencies applied.

Choosing a Weather Feed

LawnCheck retrieves weather from Yahoo! Weather, DarkSky, and Weather Underground. These services provide accurate weather information for most locations world-wide.

Select local weather from Yahoo! Weather

Local weather can be retrieved for many locations around the world from Yahoo! Weather using a WOEID location code.

To obtain a WOEID visit the Yahoo! Weather Page. Click "Change Location" and then enter your city and state. Select an item from the list displayed. Your WOEID will be displayed in the URL bar at the top of the browser.

Here's an example URL for San Jose, Ca:

The WOEID is found at the end of the URL and is: 2488042

After you obtain your local WOEID code, enter the it into the field provided on the weather setup page in LawnCheck.

Yahoo Weather provides current conditions and a forecast for both the current day and tomorrow. Yahoo does not provide PoP, but it provides daily conditions forecast which LawnCheck uses to determine whether to run or block a program based on the forecast for today and tomorrow.

Select local weather from DarkSky

Local weather can be retrieved for many locations around the world from DarkSky using a latitude/longitude coordinate as a location code.

Such a coordinate can be easily obtained from Google Maps. To obtain a latitude/longitude coordinate for your location open Google Maps and click on desired a location until you see a small panel at the bottom of the page that contains coordinates. Then click on the coordinates (they are linked). A panel will open on the left of the screen. Select the coordinates and copy them (Cntl-C for Windows) and then paste the coordinates into the DarkSky field on the weather set up page in LawnCheck. Select the "Use DarkSky" check box, then click save.

You can enter coordinates manually but if you do make sure to separate the values with a comma.

An example coordinate for San Jose CA is: 37.313372, -121.984729

DarkSky offers a weather forecast that includes current conditions and a forecast for both the current day and tomorrow. DarkSky also provides PoP (probability of precipitation) for today and tomorrow allowing a more finely grained application of blocking on precipitation. For example a program can be set to block if PoP is greater than 60% for today or tomorrow.

DarkSky offers free data up to a point. If enough LawnCheck users decide to use DarkSky we will have to charge a slight fee for its use. For now you can use DarkSky for no charge.

Select local weather from Weather Underground

Weather Underground consists of a network of local weather stations. WeatherUnderground offers a free weather feed to owners of weather stations who upload data to their network.

As of April, 2019, if you have a weather station that uploads to Weather Underground, you can obtain a PWS access key from WeatherUnderground. You can then select a local station by locating a weather station on Weather Underground's WunderMap®. You can also select your own station.

Weather Underground provides current conditions directly from your selected weather station plus a local forecast. The Weather Underground network contains stations that have rain gauges. If you select a station that has a rain gauge then you can use rainfall amounts from the station to block irrigation.

Weather Dependent Control Operation Explanation

Lawncheck provides weather dependent controls for automatic irrigation optimization, The controls are easy to use; they can be assigned to a program by clicking a checkbox on the irrigation program definition page. The controls compare the weather data received from the forecast feed with thresholds that you set for your account. Thresholds are set on the LawnCheck Weather Setup page.

The remainder of this page describes the decision logic for weather dependent programs.

Temperature Dependent Programs

LawnCheck supports temperature dependent programs including programs that deactivate in cool weather and programs that will activate in hot weather. The following explains how weather dependent decisions are made.

Cool Weather Block

If a program has a cool weather deactivation control assigned to it then the program will be blocked if the forecast high temperature for today is less than the threshold temperature that you provide. The set threshold must be greater than zero degrees. This control is very useful to prevent irrigation during cool spring or fall seasons and can save a lot of water.

The forecast high of the day is used as the determining temperature; not the run-time temperature. The forecast high of the day is indicative of the environmental evapotranspiration rate. A blocked cool cycle will be noted in the command log.

Hot Weather Activation

A hot weather program runs whenever either the run-time temperature, yesterday's high temperature, or the forecast high temperature for today OR tomorrow is greater than the set high temperature threshold. All four temperatures are checked and if any one of them is greater than the threshold, then the hot cycle will run.

We check three days worth of high temperatures to determine if the hot cycle should run. If hot weather is coming, it's generally better to apply water earlier, before the hot weather arrives because the water gets a chance to soak further into the ground.
A block will be noted in the log when a "hot cycle" does not run.

Precipitation Blocks

Local Rain Sensor

The local sensor reports it's status to LawnCheck. If the local rain sensor is indicating rain, then LawnCheck will block the irrigation cycle. The log will note a block due to local rain.

Typically a rain sensor will hold the "rain" signal "on" after rain has left the area. This is typically desirable because it helps to block irrigation after rain has stopped.

A feature of LawnCheck called RainBrain™ extends the precipitation block time up to 24 hours after the rain signal from your sensor resets. Check the RainBrain box if you wish to ensure that irrigation is blocked or reduced for up to 24 hours after precipitation.

Current Conditions Precipition Blocks

All weather services provide a current conditions status. When a weather check is made, if the current conditions code (in the case of Yahoo! Weather) is a precipitation code, then the cycle will be blocked. If the word "rain" appears in the condition code text for DarkSky or WU, the cycle will be blocked. If the current conditions code causes a cycle block, then a the block will be noted in the log.

Daily Conditions Precipition Blocks

Yahoo Weather provides additional codes including daily conditions for today and daily conditions for tomorrow. LawnCheck uses the last received daily today conditions code and saves it as "conditions yesterday." In total, four conditions codes are accumulated.

When a weather check is made, if any of the conditions codes present in the forecast (current, daily today, daily tomorrow, and daily yesterday) are precipitation codes, and "Deactivate on Precipitation in Forecast" is applied to the program, then the cycle will be blocked.

This powerful dependency can block irrigation cycles if rain is predicted for tomorrow and if rain was predicted yesterday. If this dependency is applied to a program, your cycle will be blocked before rain occurs and after rain was predicted to occur.

Probability of Precipitation (PoP)

DarkSky provides a PoP forecast in most instances. If the forecast PoP for today OR tomorrow exceeds the threshold set within the account, then the cycle will be blocked. A log entry indicating a PoP block will be made. Note: The PoP block looks at both today's forecast PoP AND tomorrow's forecast PoP. This is a great control for blocking irrigation prior to rain, but make sure to set your threshold sufficiently high for your environment.

Rain Gauge

(Only for Weather Underground) Depending on the weather station selected, the Weather Underground weather feed provides rain gauge measurements. The rain gauge data represents the 24 hour rain total. In addition, the rain gauge information is saved for one day by LawnCheck.

If the provided rain gauge data equals or exceeds the set threshold (the threshold must be set at greater than zero), then the cycle will be blocked. Because LawnCheck saves the rain gauge reading, the rain gauge reading for yesterday is also checked, and added to today's rain gauge reading to determine if the threshold is met or exceeded.

By automatically saving the the rain gauge data for one day, LawnCheck can extend irrigation blocks based on rain gauge for up to 36 hours after rain has stopped.


LawnCheck makes it very easy to select a weather provider and assign weather conditions to any or all of the irrigation programs in your irrigation schedule. The weather is applied to programs based on threshold temperatures that you set. In addition, use of forecast precipitation numbers can prevent irrigation from running both before and after precipitation has occurred.

Legal Information

Weather Underground® is a Registered Trademark of Weather Underground Inc.
WunderMap® is a Registered Trademark of Weather Underground Inc.
RainBrain™ is a Trademark of QuickSmart Devleopment